🧵 IK wrist can't rotate on one axis
Anonymous at Tue, 2 Aug 2022 03:22:05 UTC No. 911837
Hello,
I have rigged an arm with an IK target bone which works perfectly except for trying to twist the wrist on its y axis. I can parent the internal wrist bone to the IK target for rotating on the Y axis, but this causes deforming when rotating (see picrel). What should I do so I can rotate the wrist smoothly?
Anonymous at Tue, 2 Aug 2022 07:49:47 UTC No. 911867
This is where a so called twist chain or twist bone comes in. It follows in the space of the forearm and takes in the respective rotations from the wrist.
Anonymous at Wed, 3 Aug 2022 01:48:02 UTC No. 912042
>>911867
I looked that up and watched this vid: https://www.youtube.com/watch?v=LTQ
I installed a twist bone and it has changed some things but it still looks janky. Removing some of the weight painting from the forearm bone helped somewhat, but is there something else I can do to improve it?
The twist bone is the small bone to upper left of wrist
Anonymous at Wed, 3 Aug 2022 10:52:06 UTC No. 912146
>>912042
For best effect you dont install just one bone but an entire chain of bones that evenly distributes the twist through the length of the entire forearm
Anonymous at Thu, 4 Aug 2022 19:59:55 UTC No. 912399
>>912042
he installed a bone, haha
Anonymous at Fri, 5 Aug 2022 04:35:09 UTC No. 912428
>>911837
The reason that looks fucked up is because that's not how wrists work. When you rotate your hand like that, your wrist isn't twisting along that axis, it's a bone in your forearm twisting around the other, sliding on a radioulnar joint.
>tl;dr twist the forearm, bend the wrist.